PTS(4FREEBSD) - man page online | special files

NAME

pts — pseudo-terminal driver

DESCRIPTION

The pts driver provides support for a device-pair termed a pseudo-terminal. A pseudo-termi‐
nal is a pair of character devices, a master device and a slave device. The slave device
provides to a process an interface identical to that described in tty(4). However, whereas
all other devices which provide the interface described in tty(4) have a hardware device of
some sort behind them, the slave device has, instead, another process manipulating it
through the master half of the pseudo-terminal. That is, anything written on the master
device is given to the slave device as input and anything written on the slave device is
presented as input on the master device.
The following ioctl(2) calls apply only to pseudo-terminals:
TIOCPKT Enable/disable packet mode. Packet mode is enabled by specifying (by refer‐
ence) a nonzero parameter and disabled by specifying (by reference) a zero
parameter. When applied to the master side of a pseudo-terminal, each subse‐
quent read(2) from the terminal will return data written on the slave part of
the pseudo-terminal preceded by a zero byte (symbolically defined as
TIOCPKT_DATA), or a single byte reflecting control status information. In the
latter case, the byte is an inclusive-or of zero or more of the bits:
TIOCPKT_FLUSHREAD whenever the read queue for the terminal is flushed.
TIOCPKT_FLUSHWRITE whenever the write queue for the terminal is flushed.
TIOCPKT_STOP whenever output to the terminal is stopped a la ‘^S’.
TIOCPKT_START whenever output to the terminal is restarted.
TIOCPKT_DOSTOP whenever VSTOP is ‘^S’ and VSTART is ‘^Q’.
TIOCPKT_NOSTOP whenever the start and stop characters are not ‘^S/^Q’.
While this mode is in use, the presence of control status information to be
read from the master side may be detected by a select(2) for exceptional con‐
ditions.
This mode is used by rlogin(1) and rlogind(8) to implement a remote-echoed,
locally ‘^S/^Q’ flow-controlled remote login with proper back-flushing of out‐
put; it can be used by other similar programs.
TIOCGPTN Obtain device unit number, which can be used to generate the filename of the
pseudo-terminal slave device. This ioctl(2) should not be used directly.
Instead, the ptsname(3) function should be used.
TIOCPTMASTER Determine whether the file descriptor is pointing to a pseudo-terminal master
device. This ioctl(2) should not be used directly. It is used to implement
routines like grantpt(3).

FILES

The files used by this pseudo-terminals implementation are:
/dev/pts/[num] Pseudo-terminal slave devices.